.TH std::basic_string_view::find_first_of 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::basic_string_view::find_first_of \- std::basic_string_view::find_first_of

.SH Synopsis
   constexpr size_type
       find_first_of( basic_string_view v, size_type pos = 0 ) const  \fB(1)\fP \fI(since C++17)\fP
   noexcept;
   constexpr size_type                                                \fB(2)\fP \fI(since C++17)\fP
       find_first_of( CharT ch, size_type pos = 0 ) const noexcept;
   constexpr size_type
       find_first_of( const CharT* s, size_type pos, size_type count  \fB(3)\fP \fI(since C++17)\fP
   ) const;
   constexpr size_type                                                \fB(4)\fP \fI(since C++17)\fP
       find_first_of( const CharT* s, size_type pos = 0 ) const;

   Finds the first character equal to any of the characters in the given character
   sequence.

   1) Finds the first occurrence of any of the characters of v in this view, starting
   at position pos.
   2) Equivalent to find_first_of(basic_string_view(std::addressof(ch), 1), pos).
   3) Equivalent to find_first_of(basic_string_view(s, count), pos).
   4) Equivalent to find_first_of(basic_string_view(s), pos).

.SH Parameters

   v     - view to search for
   pos   - position at which to start the search
   count - length of the string of characters to search for
   s     - pointer to a string of characters to search for
   ch    - character to search for

.SH Return value

   Position of the first occurrence of any character of the substring, or npos if no
   such character is found.

.SH Complexity

   O(size() * v.size()) at worst.

.SH Example


// Run this code

 #include <string_view>

 using namespace std::literals;
 constexpr auto N = std::string_view::npos;

 constexpr bool is_white_space(const char c)
 {
     return " \\t\\n\\f\\r\\v"sv.find_first_of(c) != N;
 };

 static_assert(
     1 == "alignas"sv.find_first_of("klmn"sv) &&
       //   └─────────────────────────┘
     N == "alignof"sv.find_first_of("wxyz"sv) &&
       //
     3 == "concept"sv.find_first_of("bcde"sv, /* pos= */ 1) &&
       //     └───────────────────────┘
     N == "consteval"sv.find_first_of("oxyz"sv, /* pos= */ 2) &&
       //
     6 == "constexpr"sv.find_first_of('x') &&
       //        └─────────────────────┘
     N == "constinit"sv.find_first_of('x') &&
       //
     6 == "const_cast"sv.find_first_of('c', /* pos= */ 4) &&
       //        └──────────────────────┘
     N == "continue"sv.find_first_of('c', /* pos= */ 42) &&
       //
     5 == "co_await"sv.find_first_of("cba", /* pos= */ 4) &&
       //       └───────────────────────┘
     7 == "decltype"sv.find_first_of("def", /* pos= */ 2, /* count= */ 2) &&
       //         └────────────────────┘
     N == "decltype"sv.find_first_of("def", /* pos= */ 2, /* count= */ 1) &&
       //
     is_white_space(' ') && is_white_space('\\r') && !is_white_space('\\a')
 );

 int main() {}

.SH See also

   find              find characters in the view
                     \fI(public member function)\fP
   rfind             find the last occurrence of a substring
                     \fI(public member function)\fP
   find_last_of      find last occurrence of characters
                     \fI(public member function)\fP
   find_first_not_of find first absence of characters
                     \fI(public member function)\fP
   find_last_not_of  find last absence of characters
                     \fI(public member function)\fP
                     find first occurrence of characters
   find_first_of     \fI\fI(public member\fP function of\fP
                     std::basic_string<CharT,Traits,Allocator>)
